Is it possible to take several parts from one assembly and separate them into a sub-assembly so they can easily be used other assemblies?

An intern created an assembly of PCBs, Heatsink and fans for me.  I then built a case around it and, stupidly, saved it in the same file.  Now I want to use the initial assembly in an alternate case design.

I know I could just make a copy in a different folder and delete what I don't want to get back to original.

What I'm asking is, can I highlight those parts of the assembly I want to use and pull them out as a group to save under another name.

jerry